ASTM A193 B7 and B7M Stud Bolt Manufacturer in India
S.R. Forgings manufactures ASTM A193 Grade B7 and Grade B7M stud bolts, threaded bar in property classes 8.8 and 10.9, and mild steel studs and threaded rod, at Focal Point, Ludhiana. Standard diameters run from M12 to M75, in lengths to 1600 mm, with sizes outside that range made to customer drawing.
B7 and B7M are quenched and tempered chromium-molybdenum alloy steel, used on flange connections in refineries, petrochemical plants, power stations and process piping. The two grades share the same material. What separates them is hardness: B7M is tempered to a controlled maximum so it stays below the limit set for sour service, where hydrogen sulphide is present and a hard bolt is at risk of sulphide stress cracking. NABL-approved laboratory test reports are supplied with B7M.
Stud bolts are supplied cut to length, threaded full length or with threaded ends to drawing, and can be quoted as complete assemblies with the matching nuts. Coatings available include plain oiled, zinc plated, hot dip galvanised, zinc flake, PTFE and xylan.
B7 compared with B7M
| Grade B7 | Grade B7M | |
|---|---|---|
| Material | Chromium-molybdenum alloy steel, quenched and tempered | Same material, tempered to a higher temperature |
| Tensile strength, min | 860 N/mm² (125 ksi) | 690 N/mm² (100 ksi) |
| Yield strength, min | 720 N/mm² (105 ksi) | 550 N/mm² (80 ksi) |
| Hardness, max | 321 HB | 235 HB |
| Matching nut | ASTM A194 Grade 2H | ASTM A194 Grade 2HM |
| Where it is specified | General high temperature and high pressure flange bolting | Sour service, where the hardness ceiling for H₂S environments applies |
Manufacturing range
| Product | Diameter | Length | Standards |
|---|---|---|---|
| B7 / B7M stud bolts | M12 to M75 | to 1600 mm | ASTM A193, with A194 2H / 2HM nuts |
| High tensile threaded bar | M12 to M75 | to 1600 mm | Property class 8.8 and 10.9 |
| Mild steel threaded rod | M12 upwards | to 1600 mm | Standard sizes or to drawing |
| Studs to drawing | Mild steel, alloy steel and high tensile grades, threaded both ends or full length, to customer drawing | ||
What to tell us when you enquire
- Grade — B7, B7M, 8.8, 10.9 or mild steel. If the line is from a piping class, quote the line as written and we will read it.
- Diameter and length, and whether length is measured over the thread or overall.
- Threading — full length, or threaded ends with a plain middle, and the thread length at each end.
- Nuts and washers — studs alone, or complete assemblies with A194 nuts.
- Coating — plain oiled, zinc plated, hot dip galvanised, zinc flake, PTFE or xylan.
- Certification — mill certificate, EN 10204 3.1, NABL report, or third party inspection.
Send the flange schedule or the bolt list as it appears on your drawing. It is faster than retyping it, and nothing gets lost in translation.
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B7 Stud Bolts
ASTM A193 Grade B7 stud bolts in quenched and tempered chromium-molybdenum alloy steel, for high temperature and high pressure flange connections in refineries, petrochemical plants and power generation.
Size: M12 to M75, lengths to 1600 mm
Nut: ASTM A194 Grade 2H
Finish: plain oiled, zinc plated, hot dip galvanised, zinc flake, PTFE or xylan
B7M Stud Bolts
The same chromium-molybdenum alloy as B7, tempered to a controlled maximum hardness of 235 HB for service where hydrogen sulphide may be present. Hardness testing is carried out on every batch and NABL-approved test reports are supplied.
Size: M12 to M75, lengths to 1600 mm
Nut: ASTM A194 Grade 2HM
8.8 Thread Bar
Threaded bar in property class 8.8 for structural and general engineering work — holding down, hanger rods, bracing and tie rods.
Size: M12 to M75, cut to length up to 1600 mm
Finish: plain, zinc plated or hot dip galvanised
10.9 Thread Bar
Threaded bar in property class 10.9 where the load exceeds what 8.8 will carry at the same diameter, typically machine anchoring, heavy structural ties and equipment foundations.
Size: M12 to M75, cut to length up to 1600 mm
Note: 10.9 in long lengths is quenched with care to control bend — see our note on bolt material grades
M S Studs
Studs in mild steel, alloy steel and high tensile grades, threaded both ends or full length, manufactured to standard sizes or to customer drawing for industrial and structural applications.
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M S Thread Bar
Mild steel threaded rod in standard and custom lengths, used on transmission and telecom towers, building services, cable support and general anchoring.
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